Bartonella Infection

Bartonella species bacteria cause a range of diseases, including cat scratch disease (CSD), caused by B. henselae; trench fever, caused by B. quintana; Carrión disease (Oroya fever and verruga peruana), caused by B. bacilliformis; and bacillary angiomatosis (BA), caused by B. henselae or B. quintana.  In some cases, subacute endocarditis may also be caused by Bartonella spp. Diagnosis of these diseases is based on clinical evaluation, patient history, and laboratory testing. Laboratory evaluation may include serology, nucleic acid amplification testing (NAAT), and culture.

Quick Answers for Clinicians

What is the role of laboratory testing in the diagnosis and management of Bartonella infections?

Serology and culture are very useful to confirm a diagnosis of cat scratch disease (CSD), trench fever, Carrión disease, and endocarditis caused by Bartonella species. However, serology generally requires the comparison of paired acute and convalescent sera to confirm diagnosis. For accurate comparison of paired sera, samples should be tested in a single laboratory at the same time. Culture for Bartonella species should be incubated for at least 21 days. Because of the long turnaround time required for these techniques, treatment decisions should be informed by clinical evaluation and patient history and should not be delayed for definitive laboratory diagnosis. Polymerase chain reaction (PCR) testing may be useful to diagnose CSD, Carrión disease, and endocarditis. Carrión disease may also be diagnosed using a peripheral blood smear. PCR and blood smears are more rapid than culture or serology and may inform treatment decisions. 

How are Bartonella infections transmitted, and how does this inform diagnosis?

Cat scratch disease (CSD) is transmitted through the scratch of domestic or feral cats carrying fleas infected with Bartonella henselae. CSD diagnostic testing may be appropriate for patients exhibiting CSD symptoms with previous exposure to cats and recent scratch history. Trench fever is transmitted by the human body louse. Testing for trench fever may be appropriate in patients with characteristic symptoms who are at increased risk for human body lice (eg, persons experiencing homelessness or living in areas with poor sanitation). Carrión disease is transmitted through female sand flies, primarily in high-elevation areas of the Andes Mountains, and should be considered in patients who have traveled to that region or have been in contact with someone who has traveled to that region. 

Which symptoms might prompt testing for Bartonella?

Cat scratch disease (CSD) is often characterized by low-grade fever, enlarged and/or tender lymph nodes (1-3 weeks postexposure), and a papule or pustule at the scratch site. In some cases, eye infections, severe muscle pain, or encephalitis may occur. Trench fever generally presents with fever (one time or relapsing), headache, rash, and bone pain. Carrión disease occurs in two distinct phases. The first, Oroya fever, may include symptoms such as fever, headache, muscle aches, and abdominal pain. The second phase, verruga peruana (Peruvian warts), is characterized by the formation of growths under the skin that develop into red to purple vascular sores. Bacillary angiomatosis (BA) occurs most frequently in people with weakened immune systems (eg, patients with advanced HIV infection) and may result in lesions in or under the skin, in bone, or in other organs.

Because Bartonella symptoms are often generalized, the testing strategy should also be informed by patient history. 

Indications for Testing

Testing for Bartonella species is appropriate in patients with a compatible exposure history and typical signs and symptoms of CSD, trench fever, BA, or subacute endocarditis.  The diagnostic testing strategy should be informed by clinical evaluation and patient history.

Laboratory Testing

The laboratory diagnosis of Bartonella infection generally includes serology, nucleic acid amplification testing (NAAT), and culture. Laboratory strategy depends on the suspected etiology of disease. The CDC provides detailed testing recommendations in their information for healthcare providers. 

Serology

Serology may be useful to confirm diagnosis of CSD and trench fever. Serologic assays can be used to confirm current or past exposure to Bartonella spp.  Low sensitivity and cross-reactivity between Bartonella spp may complicate diagnosis in some cases. Observation of seroconversion between paired acute and convalescent sera is considered strong evidence of recent infection. Because diagnosis via serology requires collection of convalescent serum, treatment should not be delayed for completion of laboratory testing.

Polymerase Chain Reaction Testing

Polymerase chain reaction (PCR) testing may be useful for the diagnosis of CSD, trench fever, and BA.  PCR assays are generally appropriate for blood, cerebrospinal fluid (CSF), or tissue samples. However, sensitivity is often low in blood samples. Many PCR assays do not differentiate between Bartonella spp, which might complicate treatment selection. The sensitivity of NAAT decreases as time from initial infection increases.

Culture

Bartonella culture can be technically challenging and requires at least 21 days of incubation. Blood or tissue culture may be useful for the diagnosis of CSD, trench fever, Carrión disease, and endocarditis. 

Other Testing

Peripheral blood smear is the most common laboratory test used to diagnose Carrión disease during the Oroya fever phase.

ARUP Laboratory Tests

May confirm current or past exposure to B. henselae or B. quintana in patients with typical signs and symptoms and a compatible exposure history

Use to detect Bartonella spp in blood, CSF, or tissue

Medical Experts

Contributor

Jackson

Brian R. Jackson, MD, MS
Associate Professor of Pathology (Clinical); Adjunct Associate Professor, Biomedical Informatics, University of Utah
Medical Director, Support Services, IT, and Business Development, ARUP Laboratories

References